id is their party ID (pty_*).
Invitations
Every customer relationship starts as an invitation. It names one or more agents, the permissions you’re asking for, and optionally a per-transaction limit; the customer sees exactly what you asked for, and nothing moves until they accept. Pending invitations can be revoked, and accepted ones appear in your customer list.Acting for a customer
Each agent-customer pair carries its own permissions and limits. Depending on the grant, an agent can send and request payments on the customer’s behalf, and withexternal_accounts.create it can link the customer’s bank account.